AMPHIUMAS: Amphiumidae

PHYSICAL CHARACTERISTICS

Amphiumas (AM-fee-YOO-muhs) are very long, medium-sized to very large salamanders that look like snakes with four very short legs. These animals are dark reddish brown to gray or black on top. The belly is a lighter shade than the back or almost as dark. Adult amphiumas reach a length of 13 to 46 inches (33 to 117 centimeters), depending on the species. The legs usually are less than 0.4 inch (1 centimeter) long, and there are one to three toes on each foot.

Amphiumas have a pointed head, but the snout is somewhat flattened in two species. There are teeth on the jaw bones. Amphiumas have no eyelids and have one gill slit on each side of the body. Gills are organs for obtaining oxygen from water. Unlike the bushy, outside gills of other salamanders, the gills of amphiumas are inside their bodies, just behind the head. Gill slits are openings from the gills to the outside of the body. Gill arches support the gills inside the body.

Adult amphiumas have glands in their skin that ooze out slippery mucus. An amphiuma's tail is flat from side to side and makes up 20 to 25 percent of the total body length. A lateral (LAT-uhr-uhl) line, a system of organs that help some animals sense movement in the water, is present on the body and head of amphiumas. The bodies of these animals have fifty-seven to sixty grooves along the sides, each of which indicates a vertebra (VER-teh-bruh), or one of the bones that make up the spinal column. The vertebrae (VER-teh-bree, the plural of vertebra) are curved in on each end like the inside of a bowl. A few vertebrae near the front of amphiumas have ribs connected to them.

Amphiumas are the longest and largest salamanders in the United States. Even though local people call amphiumas congo eels, lamper eels, ditch eels, lampreys, and congo snakes, these salamanders are amphibians, not fish like eels and lampreys and not reptiles like snakes. Amphibians (am-FIB-ee-uhns) are vertebrates (VER-teh-brehts), or animals with a backbone, that have moist, smooth skin; are cold-blooded, meaning their body temperature is the same as the temperature of their surroundings; and, in most instances, have a two-stage life cycle.

Amphiumas that have gone through metamorphosis keep some features of larvae: a lack of eyelids and tongue and the presence of four gill arches with a single opening to the outside between the third and fourth arches rather than a slit for each gill. Larvae (LAR-vee) are animals in an early stage that change body form in a process called metamorphosis (MEH-tuh-MORE-feh-sis) before becoming adults. Amphiumas have lungs, but they also can breath through their throat and skin. When young amphiumas hatch, they keep their gills for a few days. Hatchlings are a little more than 2 inches (5 centimeters) long. Amphiumas that have just gone through metamorphosis may be as short as 2.5 inches (6 centimeters). Adults reach a length of 46 inches (117 centimeters).

GEOGRAPHIC RANGE

Amphiumas live in an area that extends from southeastern Virginia southward along the coastal plain and throughout Florida, westward along the coastal plain and from southwestern Alabama and all of Mississippi and Louisiana to the easternmost part of Texas and most southeastern part of Oklahoma northward to the extreme southeastern portion of Missouri.

HABITAT

Amphiumas live in swamps, marshes, ditches, lakes, and sluggish streams. One species lives in watery muck. Amphiumas can be quite common in cities, where they live in waterways such as ditches and canals. Amphiumas may hide among water plants, but they prefer crayfish holes. In rainy weather amphiumas may crawl around on wet surfaces.

DIET

Amphiumas eat worms, water insects and their larvae, frogs, salamanders, fish, and any other small vertebrates. A favorite prey is crayfish.

BEHAVIOR AND REPRODUCTION

Amphiumas are active at night and are most active when water temperatures are higher than 41°F (5°C). These salamanders wait in holes for passing prey, or they prowl in search of prey. The strong teeth and powerful bite are used to subdue prey animals. Amphiumas are eaten by snakes and large wading birds.

If a ditch or pond goes dry, amphiumas hide in holes where they lie dormant. Amphiumas have been dug from holes as deep as 3.3 feet (1 meter). Amphiumas live about twenty-seven years and can go as long as three years without food. Amphiumas periodically shed their skin and sometimes eat it. This behavior helps them stay nourished during dry spells. Amphiumas move with a side-to-side wavy motion. They are sensitive to vibrations that they detect with their lateral line system. Amphiumas out of water sometimes make a whistling sound.

Adult male amphiumas may fight during the mating season, and many have scars to show for it. During the breeding season, the cloaca of male amphiumas swells. The cloaca (kloh-AY-kuh) is the chamber in some animals that holds waste from the kidneys and intestines, holds eggs or sperm about to be released to the outside, holds sperm entering a female's body, and is the passage through which young are born. Male amphiumas make sperm from October to May. A male amphiuma courts a female by rubbing his snout against her. The female then rubs her nose along the male's body and coils her body under his, so that his cloaca is joined to hers. The male produces a sperm sac, and the female picks it up with her cloaca.

Fertilization (FUR-teh-lih-ZAY-shun), the joining of egg and sperm to start development, takes place inside the female's body. The female makes a nest in a moist place, usually under a log, leaves, or other cover. The female lays the eggs in beady strings of fifty to two hundred eggs, but there may be as many as 354 eggs in a chain. The female coils around and guards the eggs. It may take as long as six months for the eggs to hatch. The eggs and their jelly-like outer layers are approximately 0.4 inch (1 centimeter) in diameter in large species. Female amphiumas reproduce every two years.

Roommates?

In Florida, amphiuma nests have been found in the nest mounds of alligators.

AMPHIUMAS AND PEOPLE

Amphiuma meat is edible and tastes much like frogs' legs, but few people eat the meat, because the skin is difficult to strip from it. Amphiuma cells, especially the red blood cells, are the largest known cells in vertebrates, and they have long been used in physiological studies and in classrooms. The chromosomes of amphiumas also are very large and useful for study. Amphiumas are captured with dip nets, seines, minnow traps, electroshock equipment, and by hand. The skin is so slippery that cotton gloves must be used to maintain a hold on the animal long enough to place it in a container. Care in handling is recommended, because the bite can be painful.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists one species of amphiumas as Low Risk/Near Threatened, or at risk of becoming threatened with extinction in the future. Although human activity has destroyed much of the habitat of amphiumas, it also has increased habitat through the building of ponds, ditches, canals, lagoons, and lakes. Amphiumas can survive in waters with fish, and they may be major predators in some waters.

THREE-TOED AMPHIUMA (Amphiuma tridactylum): SPECIES ACCOUNT

Physical characteristics: Three-toed amphiumas have three toes on each foot. Hatchlings are 1.5 to 2.5 (4 to 6 centimeters) long from tip of snout to tip of tail. Young three-toed amphiumas that have recently finished metamorphosis are about 2.5 inches (6 centimeters) long. Adults can be as long as 40 inches (103 centimeters). The back is dark brown to black, and the belly is a lighter shade of the same color. The throat has a dark patch on it.

Geographic range: Three-toed amphiumas live in an area that extends from eastern Texas to southeastern Oklahoma, southeastern Missouri, and southwestern Alabama.

Habitat: Three-toed amphiumas live in swamps, lakes, ditches, and sluggish streams.

Diet: Three-toed amphiumas mainly eat crayfish, but they also eat other water animals.

Behavior and reproduction: Three-toed amphiumas are active at night. Although they usually stay in a small area, some of these salamanders have been known to move as far as 1,300 feet (400 meters) from their main spot.

A male three-toed amphiuma courts a female by rubbing his snout against her. The female then rubs her nose along the male's body and coils her body under his, so that his cloaca is joined to hers. The male produces a sperm sac, and the female picks up the sperm with her cloaca for fertilization inside her body. The female every two years lays 42 to 150 eggs at a time in burrows. Larger females lay larger numbers of eggs. The eggs hatch about five months after being laid. Three-toed amphiumas reach adulthood in three to four years.

Three-toed amphiumas and people: Three-toed amphiumas are edible but are rarely eaten. These salamanders are used for classroom study. Scientists have found several new species of flatworms and tapeworms in three-toed amphiumas.

Conservation status: Three-toed amphiumas are not considered threatened or endangered. ∎

FOR MORE INFORMATION

Books:

Bernhard, Emery. Salamanders. New York: Holiday House, 1995.

Duellman, William E., and Linda Trueb. Biology of Amphibians. Baltimore, MD: Johns Hopkins University Press, 1994.

Lawlor, Elizabeth P. Discover Nature in Water and Wetlands. Mechanicsburg, PA: Stackpole, 2000.

Llamas Ruiz, Andres. Reptiles and Amphibians: Birth and Growth. New York: Sterling, 1996.

Petranka, J. W. Salamanders of the United States and Canada. Washington, DC: Smithsonian Institution Press, 1998.

Web sites:

"Amphiumidae (Gray, 1825) Amphiuma/Congo Snakes." Livingunderworld.org.http://www.livingunderworld.org/caudata/database/amphiumidae (accessed on April 11, 2005).

Heying, H. "Amphiumidae." Animal Diversity Web.http://animaldiversity.ummz.umich.edu/site/accounts/information/Amphiumidae.html (accessed on April 11, 2005).

"Three-Toed Amphiuma." Smithsonian National Zoological Park. http://nationalzoo.si.edu/Animals/ReptilesAmphibians/Facts/FacSheets/Threetoedamphiuma.cfm (accessed on April 11, 2005).